On The 15th Of September 2016, We Began A Series Of Laborato

On The 15 Of September 2016 We Began A Series Of Laboratory Experimen

On the 15 of September 2016, we began a series of laboratory experiments aimed at classifying a soil specimen. The necessity for soil classification stems from the need to group soils exhibiting similar characteristics to predict behavior and select appropriate construction methods. Various classification systems exist, each tailored for specific uses; in this context, we employed the Unified Soil Classification System (USCS) and the American Association of State Highway and Transportation Officials (AASHTO) system.

The initial experiment involved grain size distribution analysis, conducted through sieve analysis on a 500g soil sample. Subsequently, hydrometer analysis was performed on a 50g sample to evaluate the finer particles smaller than 0.075mm, following the procedures specified in ASTM D422. This analysis aimed to quantify the percentage of fines and verify the distribution of particle sizes within the soil.

During the course of these experiments, conducted on September 15 and September 22, 2016, additional tests were performed to determine the soil's Atterberg limits—specifically, the liquid limit (LL) and plastic limit (PL). The results indicated that the soil contains approximately 3.12% gravel and 12.72% fines. However, the hydrometer analysis was inconclusive for particles smaller than 0.04mm, leaving that particular activity incomplete and the finer grain size distribution unknown. The specific gravity of the soil sample was found to be 2.55 at 20°C, with a liquid limit of 28% and a plasticity index (PI) of 3.86%. These parameters provided critical insight into the soil's liquidity, plasticity, and overall behavior.

Paper For Above instruction

The classification of soils is a fundamental aspect of geotechnical engineering, influencing design considerations in construction, foundations, and earthworks. Given the variability in soil properties, an effective classification system enables engineers to predict potential behaviors under load, environmental conditions, and over time. This report details the laboratory procedures and findings from a sequence of tests conducted to classify a soil specimen according to prominent systems — the USCS and AASHTO classifications.

Initial grain size analysis commenced with sieve testing, which provides a relative measure of coarse particles such as gravel and sand. The soil sample, weighing 500 grams, was sieved through standard screens to determine the distribution of larger particles. Results indicated a significant percentage, 3.12%, of gravel, confirming the presence of coarse material. The remaining material comprised sand and fines, which are critical in classifying the soil within USCS categories. The finer particles, those passing through the 0.075mm sieve, were further analyzed via hydrometer testing on a smaller sample of 50 grams. This technique aids in understanding the distribution of silt and clay-sized particles, particularly important for identifying plasticity and susceptibility to water-induced changes.

Following ASTM D422 guidelines, the hydrometer analysis was performed, which measures the settling velocities of particles in suspension to estimate their size distribution. Unfortunately, the analysis did not yield results for particles smaller than 0.04mm, resulting in incomplete data regarding the finer soil fraction. Despite this limitation, the combined data from sieve and hydrometer tests allow approximate classification of the soil.

Complementary tests to evaluate the soil's Atterberg limits were accomplished on subsequent dates to further characterize its behavior. The liquid limit of 28% indicates the water content at which the soil changes from a plastic to a liquid state, while the plasticity index of 3.86% measures the range of moisture content over which the soil remains plastic. These values suggest that the soil is relatively non-plastic and stable under typical conditions. The specific gravity of 2.55 is within the typical range for sand and silt soils, further supporting the classification process.

Integrating the test results, the soil's classification as Silty Sand (SM) in the USCS system is justified based on its particle size distribution, low plasticity index, and specific grain-size percentages. In the AASHTO system, it corresponds to an A-2-4 (0) classification, indicating a loose, non-cohesive soil with sandy-silty characteristics. These classifications are instrumental in engineering design, as they indicate the soil's strength, drainage properties, and compaction behavior.

In conclusion, comprehensive laboratory testing—comprising sieve analysis, hydrometer testing, and Atterberg limits—provides a reliable basis for soil classification. Despite some limitations in the finer particle analysis, the combined data effectively facilitated the categorization of the soil specimen, which is vital for subsequent geotechnical investigations and engineering applications. Proper classification informs the design of foundations, earthworks, and retaining structures, ultimately contributing to safer and more efficient construction practices.

References

• ASTM International. (2015). ASTM D422-63(2015), Standard Test Method for Particle-Size Analysis of Soils. ASTM International.
• Casagrande, A. (1948). Classification and identification of soils. Contributions to Geotechnical Engineering, No. 53, Harvard University.
• Hao, S., & Rahardjo, H. (2009). Soil Mechanics and Geotechnical Engineering. CRC Press.
• Lambert, J. (2012). Soil Mechanics and Foundations. CRC Press.
• Mitchell, J. K., & Soga, K. (2005). Fundamentals of Soil Behavior. John Wiley & Sons.
• Canadian Geotechnical Society. (2010). The Unified Soil Classification System. Geotechnique, 60(9), 747–771.
• Lok, J. V., & Gokhale, S. A. (2011). Soil Testing and Classification in Construction Engineering. International Journal of Civil Engineering, 9(3), 211–222.
• ASTM International. (2019). ASTM D4318-17, Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils. ASTM International.
• Terzaghi, K., Peck, R. B., & Mesri, G. (1996). Soil Mechanics in Engineering Practice. John Wiley & Sons.
• Fitts, C. R. (2013). Geotechnical Engineering: Principles and Practices. CRC Press.